A new algorithm to compute both the short-range (Lennard-Jones) and Coulomb forces in molecular dynamics based on the tree of clusters has been developed and incorporated into IMPACT. As far as we know, this work is new since until now the hierarchical algorithms have been used only to handle the long-range (electrostatic or gravitational) interactions. Although it is hard to estimate the asymptotic growth of this algorithm (it depends on both the number of particles N and the cutoff radius rc) preliminary results indicate that it scales like O(N) for fixed cutoff radius, contrary to the direct method which scales as O(N2). In previous work, we have implemented a parallel version of this method on the CM-5. We are now in the process of porting the code to the IBM